在過渡金屬材料中，鎢(W)系過渡金屬及其化合物因具有較低之電子親和能及良好的熱穩定性，故此相關材料常被應用於高溫及許多檢測儀器，如SEM、STM、TEM…等相關電子領域。因此，本論文主要所成長製備之碳化鎢(WCx)與氧化鎢(WOx)奈米線材料其於氣體感測之相關應用領域預計將具備極佳之應用潛力。
本論文旨在於氣體感測器應用之結構設計方面，氧化鎢(WOx)薄膜於傳統上即常應用於氣體感測器領域。而在本論文中，則嘗試以具高有效感測表面積之氧化鎢(WOx)奈米線材料作為氣體感測介質，藉由大幅增加之有效表面積，期能提高氣體感測器之特性表現。本研究中分別設計垂直式與水平式結構元件；水平式元件以微影系統與黃光製程再進行退火製程而完成元件，而垂直式以濺鍍沈積之三層薄膜(W/SiO2/W)輔以蝕刻及退火製程形成奈米線橋接之垂直元件結構；其中，鎢(W)薄膜為感測器電極，絕緣層(SiO2)厚度則決定了奈米線感測器之電極間距，如此則可不須考慮黃光微影所能達到之最小線寬即可獲得奈米線橋接所需之電極間距(0.2~0.3 μm)。由於，以此方式所製作之垂直式三層結構奈米線氣體感測器其感測特性係由氧化鎢(W18O49)奈米線本身之感測行為主導。而在水平式結構單一元件進行量測時之靈敏度約1.3但若進行四元件串接時其靈敏度提升至4.1，而在垂直式結構單一元件進行量測時之靈敏度約為1.06再其進行四元件串接時之靈敏度提升至3.7，六元件串接時達6.0，八元件串接更達至9.5，故預期若能串接更多數元件時其將，具備更優異之特性表現。

The gas sensors with vertically and horizontally self-growth tungsten oxide nanowires (TONs) were fabricated using sputtering deposition of pure W及WCx-70/30 wt% films followed by a simple thermal annealing process. TONs with W18O49(010) crystalline and a typical length in the range of 0.3~0.6μm were obtained and utilized as the sensing elements to NOx gas. Perfect bridging of the TONs between the two neighboring electrodes was obtained which was confirmed by SEM images and current-voltage (I-V) measurements. N-type semiconductor behavior of the grown TONs and the optimum working temperature of the fabricated gas sensors at around 200oC were also found. Our experimental results reveals that both TONs gas sensor prepared with WCx-70/30 wt% films exhibits a relatively better performances in both the sensitivity and dynamic response to NO2.

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